BGVs' EYES

In 1996, a PBGV imported into England from France was tested and found to have Primary Open Angled Glaucoma. This was the first known case in the UK. It set in motion many years of intense effort and liaison between the BGV Club, Peter Bedford Professor of Veterinary Ophthalmology and the Animal Health Trust in researching and attempting to eradicate this eye disease from the breed. Regular eye testing and now DNA testing play a large part. There has been no indication of the disease in GBGVs.

WHAT IS GLAUCOMA?

PRIMARY GLAUCOMA is an inherited canine condition. It is sub-divided into two types - Open Angle Glaucoma (POAG) and Closed Angle Glaucoma (PCAG). In both forms glaucoma results from reduced drainage of fluid within the eye, causing a build up of pressure and damage to the delicate structures within the eye. This in turn leads to pain and probable blindness.

A PBGV SUFFERING FROM POAG

Closed angle glaucoma This type of glaucoma is more difficult to detect as the problem occurs further down in the eye structure and pressures can be OK one day and escalated the next. It is more complex than POAG and may involve more than one type of mutation making it harder to find in the canine DNA. Although rare, during the screening process of PBGVs, Primary Closed Angle Glaucoma has been found.

Open angle glaucoma is a disease in which the cells that produce sight in the retina are destroyed by a slow rise in the internal fluid pressure in the eye. Normally this fluid, known as the aqueous, is constantly produced inside the eyes to feed the lens and the cornea. It is drained from the eye back into blood vessels and the production and drainage rates are balanced. In POAG it is a disturbance of drainage which leads to an accumulation of this fluid and hence the pressure rise. The sight gradually diminishes and, as the fluid pressure increases, the eye enlarges and the lens may dislocate. Eventually the dog becomes blind.

EYE TESTING The British Veterinary Association/Kennel Club Eye Scheme offers the facility of eye testing to screen for inherited eye disease. Anyone can use the information to eliminate or reduce the frequency of eye disease being passed on to puppies and, importantly, it gives early warning where treatment may be needed to delay onset.

Although any breed can be examined for eye disease, currently only the results of those breeds that appear on a list (Schedule A) produced by the Kennel Club have these included on the KC computer records and published in the KC Breed Records Supplement. The KC also publishes results of all PBGV DNA screening.

"Undoubtedly there is evidence that Open Angle Glaucoma is inherited. This disease is difficult to manage because it is often silent in its approach and, by the time the diagnosis is made, the dog's sight is badly affected and the eye may be enlarged. Once the process starts it is almost impossible to control. The earlier the diagnosis, the better the chance of effective treatment".

EXPLAINING THE EYE TESTS

​BACKGROUND As several factors were involved, for many years the BGV Club in collaboration with Prof Peter Bedford concentrated on abnormal anatomy in the drainage angle and subtle pressure rises in the eye. They therefore encouraged two types of eye testing - gonioscopy and tonometry. Only tonometry is now needed.

GONIOSCOPY (The abnormal anatomy). This is an eye examination, separate from the routine one carried out under the BVA/KC/ISDS Eye Scheme. It is done to detect glaucoma predisposition, or how likely the eye is to develop glaucoma. This test only had to be done once in a PBGV's lifetime, from 4 months old onwards. It ensured the angle was open and provided information on what is generally described at pectinate ligament dysplasia. For POAG the angle is not abnormal in clinical appearance in affected dogs and the advent of DNA testing early 2015 rendered this test unnecessary.

TONOMETRY (The pressure). This BVA/KC/ISDS regulated test, which still takes place for PBGVs, measures pressure within the eye and out-flow pressure. It aids early identification of problems such to POAG, Progressive Retinal Atrophy and Lens Luxation. It is ideally done annually, preferably up to the age of 9. Twice a year is advisable and, if a dog is related to a known "affected", every 3 months.

WHAT DO I DO AFTER I HAVE HAD MY PBGV'S EYES TESTED? When you have had your PBGV's eyes tested by one of the BVA Approved Opthalmologists, the BGV Club Health Sub-Committee would like to hear from you. Please send a copy of the eye certificate together with the appropriate consent form to Mrs Vivien Phillips, Clipperdown Cottage, Beacon Road, Ringshall, Berkhamstead, Herts, HP4 1NF (01442 851225 or vphillips@btinternet.com).

*** It is important that once your PBGV's test is completed, whether the first

or any follow-up check, you send the eye certificate with consent form

WHAT RECORDS DO THE BGV CLUB HOLD? From 2006 the BGV Club committee compiled a full record of all BGVs who had undergone eye testing. For a small fee to cover printing and postage, this was made available in booklet form to club members, with the BGV Club retaining full copyright and a restriction on reproduction. The aim of making the information available to members was to help breeders in their selection of sire and dam in an effort to control POAG in the breed.

In 2014 this method of maintaining a track on PBGV eye health was superseded by the exciting advent of DNA testing and the official publication of results.

DNA TESTING

In the UK, the PBGV is currently the only breed certified for POAG under the Eye Scheme. After many years' research, in 2014 the AHT gave the exciting news that they had identified the genetic mutation responsible for POAG in PBGVs. Since early 2015 a DNA test has been available. This test largely obviates the need for gonioscopy and will be invaluable in eradicating the disease from PBGVs as there is no predisposing factor that can be screened for by eye examination before the onset of the disease.

DNA TESTING RESULTS

Each month the AHT gives the BGV Club statistical information on how many

DNA tests by country have been carried out to date. They also provide a list of those countries from which less than 5 samples have been received. This may possibly be because the breed is numerically small in some countries.

TOTAL NUMBER OF PBGV DNA TEST RESULTS UNTIL 16 JULY 2018

ANSWERING YOUR QUESTIONS ABOUT DNA TESTING

DO ALL PBGVs NEED TESTING REGARDLESS OF AGE? YES!!! Certainly all breeding stock should be tested. However, in the knowledge that a clear to a clear mating will produce all clear puppies, consider which PBGVs need to be tested. If you own several you may not need to have all of them tested as you may be spending money unnecessarily. Look at your pedigrees and start with the older hounds. In many cases this will entail liaison between breeders where one has used another's stud dog. If both sire and dam are tested clear, off-spring from that mating will automatically be hereditary clear, thus no need to test them. However, with the various possible permutations, any other than progeny from two clear parents will require testing to establish their status. This is especially important with those destined for reproduction, as the key to managing genetic conditions with a DNA test through successive generations is in knowing exactly where the faulty copies of the genes are.

IF A BREEDING BEWEEN TWO CLEARS BEARS NO RISK, WHAT ARE THE CONSEQUENCES OF OTHER MATINGS? This chart shows the likely outcomes of various breedings:

For example, a carrier can still be used for breeding purposes but the carrier will need to be put to a clear to avoid producing affected offspring. The resultant litter from such a mating would produce on average 50% carriers for the mutation. Although statistically two carriers will produce affected and clear, this isn't guaranteed. Each dog carries one good and one faulty gene, so there is a chance that both sire and dam passed on their good gene.

As a breeder, even if you endorsed your puppies "Progeny not eligible for registration", based on known test results of the parents, if your litter is other than 100% clear, it will be your responsibility to contact those who bought a puppy from you, advising they get their PBGV's DNA analysed if they intend breeding - and making them alert to the possible consequences of reckless breeding.

SO SHOULD WE BREED FROM CARRIERS? Cathryn Mellersh at the Animal Health Trust produced a valuable and useful paper on the subject giving advice that carriers should always be included in the first one or two generations that follow the launch of a DNA test for a recessive mutation.

This is regardless of the frequency of the mutation as it gives breeders the opportunity to capture desirable traits, such as breed type and temperament, before they start to select for dogs that are clear of the mutation.

WHAT IS THE DIFFERENCE BETWEEN ORDERING SWAB KITS AND ORDERING SWAB TESTING? The Animal Health Trust will provide swab test kits free of charge if you let them know how many you need by e-mailing them.

When you have a kit and have swabbed your PBGV's mouth, you can order the actual swab testing and analysis by going on the AHT website www.ahtdnatesting.co.uk/ inserting your hound's registration details and microchip number - and any discount code you may have - then paying for the test on-line by credit or debit card.

IS VETERINARY OR OTHER RESPONSIBLE CONTROL NEEDED WHEN SWABBING? The AHT will accept swabs done by the owner, though their on-line form contains space for a vet to confirm that he/she has checked the microchip number during swabbing, if you so wish.

DO I GAIN ANY BENEFIT FROM BEING AN ASSURED BREEDER? As a Kennel Club ABS member, you are entitled to a discount. Go onto the Kennel Club's MyKC site, log on, go to the Special Offers page and there you will find a 30% discount code from the AHT for their DNA tests for genetic diseases.

DO ANY CONDITIONS APPLY FOR AN ASSURED BREEDER? As a Kennel Club ABS member, you are obliged to DNA test your PBGVs. This became effective from 20 July 2016 and there was a six months’ grace in which to comply. It will not be necessary for those who breed from a clear sire and clear dam, as the offspring will be automatically clear.

THE AHT ALREADY HOLDS MY PBGV'S SWABS, DO I NEED TO RE-SUBMIT?

If a sample has been used in the AHT's research and contributed towards finding the causal mutation, they usually report their findings directly to the owner after a DNA test is launched. For PBGVs, only a few cases were used to achieve this goal. PBGVs whose eyes are OK were not needed. While an increase in the intra-ocular pressures would indicate a case, an absence of this increased pressure doesn't necessarily indicate an unaffected control - the PBGV could be a carrier.

Submissions for DNA testing should ideally be traceable from when the order is placed through to providing the result. An exception to this is where a new sample is unobtainable because the dog has passed away since the research sample was submitted. Ask the AHT if you want a Letter of DNA Analysis and give a donation to help with the cost of analysis.

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​What are Hot Spots?

Like a moist dermatitis, hot spots can be a problem in warmer weather. An area of skin becomes inflamed and infected appearing as a moist, oozing, reddened area that is painful and very itchy for your dog. Any licking, chewing or scratching the area worsens the condition dramatically.

HOW DO I FIND OUT THE STATUS OF A PBGV WHEN CONSIDERING A MATING OR BUYING A PUPPY? DNA test results are gradually fed through from the AHT to the Kennel Club.

You can also view information on any dog, including health checks. Log onto www.mykc.org.uk (if necessary by requesting a new account by inputting a Username and Password). To find details, go to Tools and Resources at the top and click on that. Then Look Up a Dog, click on the breed name. Then enter the name of the dog. Alternatively you can view a BGV's health status by going onto the Kennel Club's Mate Select Health Test Results Finder.

Another useful source of information can be found on the PBGV Club of America website which gives details of all PBGVs either registered with the AKC or shown in American PBGVs' pedigrees. The information includes DNA test results.

WILL I STILL NEED TO GET MY BGV's EYES TESTED? YES!!! DNA testing is not an alternative to clinical testing but rather a tool to be utilised by breeders in conjunction with their normal selection criteria of conformation, temperament etc. Any dog or bitch intended for use in breeding should continue to be clinically screened on a regular basis. Certainly an eye examination before breeding is advisable in case there is a problem and continued regular testing will highlight any problem.

MOST IMPORTANTLY, even if you have obtained a DNA analysis, bear in mind that causes of glaucoma can be genetic or acquired, such as infections or trauma (known as secondary glaucoma). Your PBGV may be predisposed to a combination of genetic mutation and a concurrent acquired eye disease. In addition, with evidence that POAG can present in older dogs, eye testing into old age on an annual basis is therefore extremely desirable. Great strides have been made in detecting the gene that causes the mutation leading to POAG and, while there is certainly no need for alarm, bear in mind that this is an evolving science and there may always be the exception that proves the rule. If a problem is found early, there are remedies which may increase the length of time that your PBGV's eyesight remains good.

Eye testing should still take place, as there are other eye diseases that might be detected. Picking them up early will help prevent it becoming an issue for the breed in the future.

Within the first year over 1,050 PBGVs worldwide were DNA tested by the Animal Health Trust and now approaching 2,000.

If you have any questions about the DNA testing for PBGVs, contact either